How to animate a character walking around?
Rigify and MHX use a bone called master. In order to apply poses independently of position and orientation the master bone which must not be added to the poses. 
Parenting the rig to an empty might also work.





When the feet start to slide around the walkcycle is too slow for use with the movement. In this case you can select the walkcycles keyframes and scale them until it looks right.